Tool-wear effect compensation under sequential tolerance control

The production of functional parts requires component dimensions and other geometric features to be produced within their tolerances. In order to achieve the allowable variation in the final dimensions of the part, it is necessary to reduce the variation of manufactured dimensions. Sequential tolerance control, which is predicated on the ability to measure the output of prior operations, has been developed to compensate for the effect of non-repeatable (random) variation in process outputs. Random variation, however, is not the only disturbance that affects a process. Cutting tools wear with time, creating a gradual loss of cutting tool material that introduces a systematic variation in the output of the machining operation. This paper proposes the use of acquired measurement information to compensate for both random and systematic (tool wear) variation where appropriate.